The invention relates to a vacuum valve with a valve rod which has a longitudinal axis and which carries at least one closing member for closing at least one valve orifice and which can be displaced by a longitudinal drive, in a longitudinal direction lying parallel to the longitudinal axis of the valve rod, from an initial position, in which the vacuum valve is open, into an intermediate position, and can be displaced by a transverse drive from the intermediate position to at least one end position in which the vacuum valve is closed.
Vacuum valves, in which a closing member can be moved from an open position through a middle position, in which the closing member overlaps a valve orifice, but is lifted off from the valve seat, into a closing position, are designated as L-valves. In addition to designs in which the adjustment of the closing member from the middle position into the closing position takes place as a result of pivoting of the valve rod carrying the closing member about an axis lying at right angles to the valve rod, designs are also known in which rectilinear adjustment of the closing member between its middle position and its closing position takes place. For example, designs are known in which a carrying unit is fastened to the valve rod, the closing member being adjustable with respect to the carrying unit by means of piston/cylinder units. Such designs may be gathered, for example, from US 2007/0272888 A1 and U.S. Pat. No. 6,899,316.
US 2008/0017822 A1 discloses an L-valve in which the closing member is attached to a valve rod which is guided displaceably in its longitudinal direction and can be displaced in the longitudinal direction by means of a longitudinal drive formed by a piston/cylinder unit. By means of a guide device, which in one embodiment is formed by a linear guide, this piston/cylinder unit is guided displaceably in a transverse direction at right angles to the longitudinal direction, with the result that the valve rod can also be displaced in the transverse direction. To adjust the valve rod in the transverse direction, there is a piston/cylinder unit integrated into the closing member. In a further embodiment, the transverse drive device is formed by a piston/cylinder unit which is arranged outside the vacuum region and which acts upon the cylinder of the longitudinal drive device. It is stated that such an embodiment is suitable particularly for applications in which the closing member is acted upon only by a differential pressure which presses the closing member onto the valve seat. In this case, there is no need for a high closing force pressing the closing member onto the valve seat to be applied. A transmission of a higher closing force would present problems with the transverse guide which may be gathered from this publication.
An L-valve of the type initially mentioned may be gathered from WO 2010/034046 A1. The valve rod of cylindrical cross section, in the exemplary embodiments shown there, is guided displaceably in its longitudinal direction directly by a guide unit which is itself guided by a bearing unit displaceably in the transverse direction lying at right angles to the longitudinal direction of the valve rod. The guide unit is of relatively robust form in order to allow good guidance and also forms cylinder spaces for the longitudinal drive displacing the valve rod in its longitudinal direction.